Some binding modes of 2-aminopyridine to ruthenium(II) fragments

The bonding modes of 2-aminopyridine (apy)(1 equiv.) with some ruthenium(II) fragments were studied. In the reaction with [RuCp (CH3CN)3]+(1) one acetonitrile ligand is replaced with apy being (kappa)1(N-pyridine) bonded. This complex is very air-sensitive transforming into dinuclear [RuCp(µ3-dapy)]22+ where dapy is deprotonated apy. On the other hand, [RuCl2(PPh3)3] exchanges one phosphine ligand for apy which is coordinated in the (kappa)2N,Nʹ mode. Similar to 1, the complexes [RuCp(CH3CN)2L]+(L = PMe3, PPh3 or CO), also react with apy to give [RuCp(CH3CN)(L)((kappa)1N-apy)]+. These compounds were reacted with HC(identical)CPh with appreciable differences depending on L. While with L = CH3CN no clean reaction took place, with L = PMe3 an (eta)3-allyl carbene is formed with release of apy. With L = PPh3 or CO, dapy stabilizes a Fischer carbene through chelation. Finally, if 1 is reacted with 2-N,N-dimethylaminopyridine (dmapy), all acetonitriles are displaced in favor of (eta)6-coordinated dmapy.